Hi Lori. Yes, there is such a thing as not eating enough. From the reading I have done, you should be eating 10-12 times your body weight in calories. So take your weight, multiply it by 10, and that is approximately how many calories you should eat. I am on a major stall right now, have been for about 4 weeks. But I haven't let it worry me. I feel really good and my clothes are fitting better. I had a couple of bad days this week, but I started on induction yesterday, to jumpstart me again. Hopefully that will work.
I eat Atkins bars once in awhile, but not often because of the hidden carbs. I only use them as emergencies when I am out.
Hope this helps.

Glenda